**3.3 Remotely operated vehicle**

A remotely operated vehicle (ROV, **Figure 6**) is an unoccupied underwater robot that is connected to a mother ship by a series of cables. A load-carrying umbilical cable is used along with a tether management system (TMS) when the ROV works in rough conditions or in deeper water.

Before the ROV dives, it requires a relatively accurate understanding of the topography of the working area. Usually, the topographical map of the working area is obtained by a shipborne deep-water MBE. However, for deep sea areas, the accuracy of shipborne deep-water MBE is limited. To ensure safety of the ROV when the topography of the seafloor is complex, it is necessary to use micro-topographical

**Figure 5.** *Autonomous underwater vehicle.*

**Figure 6.** *Remotely operated vehicle.*

mapping sonars mounted on the ROV to obtain fine topographical map of the working area. However, unlike DT and AUV, ROV is not suitable for large-area mapping surveys.
